This invention relates to a disc brake.
A disc brake is known, in which a brake disc is held through the medium of brake pads between one arm of caliper and a piston shifted due to hydraulic pressure from a dual system.
Some of the disc brakes of this type are so constructed that the piston and the cylindrical member serving to guide the piston define two oil chambers, into each of which hydraulic pressure is introduced from separately provided hydraulic pressure systems. The present invention is directed to improvements in a disc brake of this type.
In a disc brake of this type, in the event that pressure in one of the hydraulic systems fails to increase due to trouble in the hydraulic system, a force will act on the cylindrical member in a direction moving the cylindrical member from the bottom wall face of the cylinder. In this connection, the disc brake of the prior art involves the problem of the necessity of providing a locking construction for the cylindrical member, such locking construction often failing for lack of strength.
Furthermore, in the disc brake of the conventional type a locking ring fits in an annular groove provided in the side wall of the cylinder. It is troublesome to manufacture these parts and to assemble the same. In addition, in replacing a broken seal there is risk of scratching the inner wall of the cylinder, which might impair the sliding motion of the piston in the cylinder.